GB2124519A

GB2124519A - Repairing coke oven or combustion chamber walls

Info

Publication number: GB2124519A
Application number: GB08314640A
Authority: GB
Inventors: Yoshihiro Omae; Kunio Ishikawa; Takahisa Fukao; Katsushige Yoshida
Original assignee: Mitsubishi Kasei Corp
Current assignee: Mitsubishi Kasei Corp
Priority date: 1982-05-27
Filing date: 1983-05-26
Publication date: 1984-02-22
Also published as: JPH0517277B2; IT1162867B; IT8367585A0; GB8314640D0; DE3318563C2; BE896867A; DE3318563A1; JPS58206682A; GB2124519B; AU1500683A; AU560125B2; US4577385A; CA1231226A

Description

GB 2 124 519 A 1

SPECIFICATION

A method and apparatus for repairing a wall of a combustion chamber or coke oven This invention relates to a method and apparatus for repairing damage to a wall of an enclosed chamber or structure in which a fuel is burned to provide heat, such as, for example, a coke oven or a combustion chamber in a coke oven battery.

At present coke ovens are constructed chiefly of refractory bricks because they are subjected to extremely high temperatures. A coke oven undergoes external mechanical force, thermal stress and various other effects resulting from carbonisation of the coal charge, coke oven gas and the like. Therefore, damage is caused at various parts of the coke oven while it is in use over a long period of time. More particularly, the walls of the coke oven are liable to suffer damage, because the various effects resulting from the above factors are concentrated on the walls.

When the wall of the coke oven is damaged, the damage to the wall must be repaired by spraying mortar. If the wall is damaged to a large extent, the refractory bricks must be changed. In this regard, it is necessary to examine to what extent the wall of the coke oven or combustion chamber is damaged. Furthermore, the condition of the damaged area must be determined exactly.

In the past, the damaged area of a wall is detected by peeping at the inside of the oven from the front in the case of a coke oven or by means of an inspection hole in a combustion chamber, by eye. By this method, it is not easy to detect either the location or the extent of any damage accurately. Furthermore it is not desirable to conduct the examination of a coke oven by eye under the hard working environment with its high temperatures. Furthermore, when damage is detected, the repair work must be conducted from 105 inside of the coke oven while covering the wall opposite to the wall to be repaired with a heat insulating material. Thus, repair work in the past is troublesome, time consuming and hazardous because it must be done under high temperature 110 conditions etc.

Accordingly, it is an object of the present invention to provide a convenient method and apparatus for inspecting a wall of a coke oven or combustion chamber to detect any damage.

It is another object of the present invention to provide a method and apparatus for repairing damage to a wall of a coke oven or combustion chamber quickly and reliably without having to enter into the interior of the coke oven or 120 combustion chamber.

According to one aspect of the invention, there is provided a method of repairing a damaged wall of a combustion chamber or coke oven which comprises inserting a lance into the chamber; inspecting the condition of the wall by means of an optical system within the lance; transmitting an image of the wall condition to a location outside the chamber; and spraying repairing materials via the lance through a nozzle on to any damaged areas detected.

According to another aspect of the invention, there is provided apparatus for repairing a damaged wall of a combustion chamber or coke oven which comprises a lance including an optical system, an elongate conduit and a nozzle, the optical system comprising means for transmitting an image of the wall condition to a location outside the chamber when the lance is within the chamber, and the conduit being arranged to connect the nozzle to a source of repairing material whereby the repairing material may be sprayed on to the damaged areas.

The invention may be carried into practice in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is an elevation of repair apparatus in accordance with one embodiment of the present invention; Figure 2 is a sectional plan view taken along the lines 11-11 of Figure 1 looking in the direction of the arrows; Figure 3 is a diagrammatic top plan view of the apparatus shown in Figure 1; Figure 4 is a plan view of a lance portion of the apparatus extending into the interior of a coke oven; Figure 5 is a cross-sectional view to an enlarged scale taken along the lines V-V of Figure 4; Figure 6 is a partial longitudinal sectional view of the front end of the lance; Figure 7 is a longitudinal cross-sectional view of a modification of the lance; Figure 8 is an elevation of another embodimen of the entire apparatus; Figure 9 is a side elevation of the apparatus shown in Figure 8; Figure 10 is a cross-section to an enlarged scale of the lance portion of the apparatus shown in Figure 8; Figure 11 is a cross-sectional view taken along the lines XI-XI of Figure 10; Figure 12 is a cross-sectional view taken along the lines XII-XII of Figure 10; Figure 13 is a cross-sectional view taken along the lines XIII-XIII of Figure 10; Figure 14 is a plan view of a modification of the supporting apparatus for the lance; and Figure 15 is a side elevation of the apparatus shown in Figure 14.

Referring to Figures 1 to 3, there is illustrated an apparatus for detecting and/or repairing damaged area on a wall of an enclosed chamber or structure in which heat is produced, as by burning fuel, for producing coke and the like. The apparatus includes a lance 1 for detecting and/or repairing any damage. The lance 1 is provided with a reinforcement rib 2 and wire 7 stretched above the lance 1. In addition, there are provided a rack 6a on the underside of the lance 1, a camera 8 and a balance weight 9 at the rear end of the lance 1. The lance 1 is movable on side rollers 3 in GB 2 124 519 A 2 both forward and rearward directions by means of a pinion 6b which engages with the rack 6a and causes lance to advance into the enclosed chamber, such as, for example, a coke oven or chamber, for detecting the damages on the wall. 70 The lance 1 is axially supported on bearings 5 mounted on a platform 4 so as to be able to tilt by means of a gear 10 which is driven by a motor 11.

Reference numeral 12 denotes hydraulic cylinders which give up-and-down movement to the platform 4. The cylinders 12 are mounted on a truck which is propelled by means of wheels 15 to be driven by a motor 16. In addition, a heat shielding wall 13, an air tank 14, a cooling water tank 17, a feeder 18 of repairing materials, an oxygen cylinder 19, an oil tank 20, a monitoring television receiver 21, and a control panel 22 are arranged on the truck as shown in Figures 1 and 2.

The inside structure of the lance 1 is as shown in Figures 5 and 6. Figure 5 shows a cross sectional view of the lance 1 taken along the lines V-V of Figure 4, whereas Figure 6 shows a cross-sectional view of the muzzle or front end of the lance 1 corresponding to the portion which is encircled by the dotted-line VI in Figure 4. As shown in Figures 5 and 6, the lance 1 includes a viewing window 24 made of quartz, an infrared absorption filter 25 attached to the rear surface of the window 24, a conduit 26 having a nozzle at its end which is directed to an opening 1 a of the lance 1 for blowing air or oxygen gas and is connected to the air tank 14 or the oxygen cylinder 19 by means of a valve, and a conduit 27 having a nozzle at its end which is directed to the opening 1 a of the lance 1 for spraying material to 100 repair the damage on the wall. The conduits 26 and 27 run continuously within the lance 1 from the rear end to the front end thereof. The lance 1 further includes a light guide 31 and an image guide 32 which are made of optical fibre bundles. 105 The light and image guides 31 and 32 run continuously within the lance 1 in the same manner as the conduits 26 and 27, and the terminating end of the light guide 31 is directed 45 toward the opening 1 a of the lance 1 as shown in 110 Figure 6. The image guide 32 is provided with a lens 33 at the terminating end thereof which is directed opposite to a reflector 34. The lance 1 has an outer shell of a heat insulating material 28, and a cooling system which comprises a cooling 115 water supply pipe 29 and a cooling water recovery pipe 30 each connected to the cooling water tank 17, in order to protect the optical system and conduits through which the fluids and discrete materials flow against heat.

In Figure 3, reference numeral 35 designates a supply tube for the repair material in the form of a flexible hose one end of which is connected to the conduit 27. The supply tube 35 is wound around a drum 36 mounted on the platform 4 and the other end of the supply tube 35 is connected to the feeder 18 of repair material. Thus, the supply tube 35 can be wound off the drum 36 when the lance 1 is advanced, and when the supply tube 35 becomes slack due to the retraction of the lance 1, the drum 36 rotates to wind up the loose supply tube 35. The supply tube 35 extending from the drum 36 to the feeder 18 is not shown in Figure 1, because it is located behind the control panel 22.

Reference will now be made to the repair of a coke oven using apparatus as described above. The apparatus shown in Figure 1 is moved by energising the motor 16 to drive the wheels 15 so that it may be located in front of the door either at the coke side or the pusher side of the coke oven to be examined. Then, the station 4 is moved vertically by means of the hydraulic cylinder 12 while adjusting inclination of the lance 1 by energising the motor 11, thereby maintaining the lance 1 horizontal at a predetermined height. Next, the lance 1 is advanced by rotating the pinion 6b and introduced into the coke oven through the front opening as shown in Figure 4 so that the opening 1 a formed at the front end of the lance 1 may be directed at the wail 41 to be examined in the coke oven 40. The wall 41 is then exposed to light emitted from the terminating end of the light guide 3 1. The light reflected from the wall 41 passes through the viewing window 24 and the infrared absorption filter 25 and reaches the reflector 34. The reflector 34 reflects an image of the wall 41 and the image is focused on the end surface 32a of the image guide 32 by means of the lens 33. 95 The image formed on the end surface 32a of the image guide 32 is transmitted to the other end of the image guide 32 where a photograph of it is taken by the camera 8 or it is observed by means of a monitoring television receiver 21. Instead of observation on the television, the image may be observed by means of an eyepiece. In this manner, the state of the wall in the coke oven is observed from outside the coke oven so as to detect locations where the wall is damaged. This detection can be easily and quickly made. When the damaged area on the wall is detected in this manner, the position of the lance 1 is adjusted so that the nozzle 27 may be directed to the exact location where the wall is damaged. Then, fine particulate materials contained in a feeder (not shown) are blasted from the nozzle 27 through the supply tube 3 5 by using compressed air, gas liquid or the like so that the damaged area on the wall may be subjected to abrasion. After finishing the abrasion, the supply tube 35 is switched to be connected to the feeder 18 of repairing material, and the repairing material is sprayed from the same nozzle by using compressed air, gas or liquid or the like against the damaged area on the wall. Thus, the repair of the damaged area on the wall is accomplished.

When repairing the damaged area on the wall, it is preferable to position the lens 33 and the nozzle for spraying the repairing material in such a way that the repairing material is directed from the nozzle to the centre of the position observed, because this makes it possible to spray the repairing material at the damaged area on the wall in the centre of viewing range. As a result, the damaged area on the wall can be repaired h 3 GB 2 124 519 A 3 accurately.

The fine particulate material used in the sandblasting step must be sufficiently heat resistant and hard when it is in use, and examples of such a material are corundum, energy, garnet, quartz sand, spinel, alumina, zirconia, silicon carbide, boron carbide, boron nitride, grit, shot and the like. The diameter of the particulate material used is 0.1 to 5 mm, preferably 0.3 to 3 mm. The blast of the fine particulate material is effected under such 75 conditions that the ejection pressure from the nozzle is 2 to 20 kg/cm' G, preferably 3 to 10 kg/cm' G and that the ejection velocity is 0.5 to 5 km/s, preferably 1 to 2 km/s by adjusting the pressure of compressed fluid and the nozzle size orifice. The repairing materials preferably include materials which are easily oxidised. When the repairing material is to be sprayed in a molten state caused by combustion, either oxygen gas or air is ejected from the nozzle 26.

After finishing the repairing work to one damaged area on the wall, the lance 1 is advanced further in the coke oven to continue the inspection and where necessary, the repair of other damaged areas on the wall. When the observation and repair of damage at a certain height of the wall is completed, the platform 4 is shifted to a plane of different height by means of the hydraulic cylinder 12 to conduct the inspection and repair of damage at that height in the same manner. Thus, the entire wall of the coke oven can be inspected and repaired.

Damage to a wall usually occurs at a joint between bricks. Accordingly, it is advantageous to actuate the hydraulic cylinder 12 and the pinion 6b so that the lens 33 of the lance 1 may travel along the joints by having locations of the joints memorised in a computer. This makes it possible to reduce significantly the time required for inspecting and so repairing the wall.

In this process, the lance 1 is subjected to the forward and backward, and vertical movements. The feeder 18 of the repairing material is fixed to the truck and does not move. Thus, the relative position of the lance 1 and the feeder 18 changes during the inspection and/or repairing operation this being permitted by the supply tube 35 which is flexible and connects the lance 1 to the feeder 18 thus allowing the lance 1 to move freely.

Furthermore, the drum 36 rewinds the supply tube 115 to prevent the supply tube from becoming an obstacle if the distance between the lance 1 and the feeder 18 becomes short and the supply tube would otherwise become slack. On the other hand, the drum 36 permits the supply tube wound on 120 the drum 36 to be unwound without slackening when the lance 1 is advanced so increasing the distance between the lance 1 and the feeder 18.

Thus, there is no possibility that the slackened supply tube entangles the lance 1 to cause the movement of the lance to be checked, and the lance 1 can be moved smoothly.

In this embodiment, the cooling water supply pipe 29 and the cooling water recovery pipe 30 are arranged within the lance to protect the light 130 guide 3 1, the image guide 32 and so on against heat by circulating cooling water from the tank 17.

Thus, the lance 1 is not damaged if it is inserted into a coke oven, at a high temperature.

It may be difficult to discriminate between a brick and its joint in a coke oven wall if there is no significant difference in brilliance. In this instance, in order to make discrimination easy, the surface to be observed is irradiated by light emitted from the light guide 31 or a light source (not shown) directly inserted into the coke oven, and the incident radiation in the infrared spectrum entering into the image guide is absorbed in the filter 25. In a positive alternating method of making discrimination easier, air is blown on to the wall of the coke oven from the diagonal or front direction through the nozzle for blowing the air or oxygen gas, thereby making the brilliance different due to the difference in temperature between the brick and the joint. If there is a crack in the joint, the difference in temperature between the brick and the joint becomes marked, which makes discrimination easy. It is possible to use nitrogen gas as the fluid to be blown against the wall instead of the air, though air is preferable, because it makes a more marked difference between the brick and the joint. Presumably, this is because temperature at the crack portion in the joint becomes higher due to combustion of carbon which is deposited on the crack portion at a higher rate. As an alternative to air, oxygen gas or other gases containing various concentration of oxygen can be used.

Generally, the lance mounted on the platform lies in a position which is higher than the bottom wall of the coke oven in view of the relative positions of the coke oven and service benches. Accordingly, it is impossible to observe and repair the damaged parts of the wall which are at a position lower than that of the lance when the lance is at its lowermost position following the method described above. In this instance, the lance 1 is tilted from the horizontal position by rotating the gear 10 in order to effect inspection and repair of areas which lie at a position lower than the lowermost position of the lance when horizontal.

The lance 1 of the above embodiment includes an elongate cylindrical body which extends longitudinally within the coke oven to its centre when the lance is inserted into the coke oven from the doorway at either the coke side or pusher side of the coke oven. Thus, the entire length of the lance 1 must be moved when examining the wall in the coke oven.

Figure 7 shows a lance 1 of telescopic structure which changes its length in order to move the lance tip within the coke oven. This structure also makes it easier to move the lance when outside the coke oven. The detailed structure of this lance will be explained hereinafter with reference tb Figures 8 through 13. In the lance of telescopic structure, it is not preferable that the conduit for supplying the air or oxygen gas and other pipes or tubes disposed within the lance are made of hard 4 GB 2 124 519 A 4 material, such as a metal. All of the tubes including the tubes for protecting the light guide or image guide and the gas supply tube connected to the air or oxygen gas spray nozzle are made of a flexible heat resistant material. The flexible tubes are wound on a drum which is mounted on the truck and which is similar to the drum 36 shown in Figure 3, so that the flexible tubes may not obstruct the movements of the lance and the platform.

The method of inspecting and repairing the wall of the coke oven by inserting the lance into the coke oven from the doorway is the same as in the earlier embodiment.

In an alternative method, the inspection and repair of the wall of the coke oven can be effected by inserting the lance into the coke oven from the top of the oven through the charging holes of the coke oven or the inspection holes of a combustion chamber.

The methods of spraying the repairing materials which are applicable to the method of the present invention include; a wet method in which particulate mortar is sprayed while being mixed with water; a thermal spraying method in which the particulate mortar is sprayed in a molten state, the mortar being melted by a high temperature gas flame; and a method of spraying the particulate mortar as it is. In addition to the mortar, a mixture of metal oxide and glass raw material powders, and a mixture of metal oxide and glass raw material powders to which an additional metal powder is added can be used as a repairing material. As explained above, the spraying of these repairing materials is effected by the force of a pressurised liquid, air or gas. Thus, if water is used as the liquid, the wet method is employed, while if a carrier gas is used, it will be the thermal spray method.

In the embodiment explained the above reference has been made as to the method of observing the image which is transmitted through the optical fibres (image guide 32) disposed within the lance 1 from the outside of the coke oven. It is to be understood that a television camera 8 may be used to observe the image at a position outside of the coke oven. In this instance the image formed by the lens 33 arranged at the front end of the lance is taken by the television camera and is observed on a monitor television receiver outside of the coke oven. It is also to be understood that the image may be recorded or memorised on a videotape or in a computer so that it may be reproduced to repair automatically the damaged area of a wall. More particularly, the position of the damaged area of the wall, its shape and size are recorded on the videotape, or in the computer when the entire wall or a predetermined area is inspected. The repairing apparatus is then operated automatically based on the information stored in the recording device to repair the damage to the wall. In this method, the steps of detecting and repairing the damage to the wall - can be effected sequentially and separately.

In the apparatus shown in Figure 6, the infrared130 absorption filter 25 is attached to the rear surface of the window. It is to be understood that the filter 25 may instead be located between the reflector 34 and the lens 33 or the image guide 32 and the camera 8. Also the light condensing system which comprises the reflector, prism, lens etc. and which are disposed in the lance individually, may be disposed in the lance as an assembly. It is to be understood that a total reflection prism may be used instead of using the reflector 35. In the above embodiment, the detecting apparatus is mounted on the special truck; alternatively, the detecting apparatus may be mounted on a pushing machine, guide car or charging car.

Referring to Figures 8 to 15, there is shown a modified form of apparatus which includes a first lance 10 1 and a second lance 102 for detecting and repairing the damage to the wall. The first lance 101 is telescopically inserted into the second lance 102 so that it may slide into or out of the second lance 102. The second lance 102 is supported by a lance supporting apparatus 103 which gives horizontal and vertical movement to the second lance 102. The second lance 102 is held by four rollers 106 mounted on the lance supporting apparatus 103 which support the second lance 102 horizontally from the upper and lower directions. The second lance 102 is advanced or retracted horizontally by rotating the rollers 106 by any suitable driving means (not shown). The lance supporting apparatus 103 is mounted on a mast 107 rising vertically from a truck 109 and can move vertically by means of gears 104 and rollers 105 which engage with both the front and rear surfaces of the mast 107. The vertical movement of the lance supporting apparatus 103 is effected by rotating the gear 104 by any suitable driving means (not shown) or directly pulling up or down the lance supporting apparatus 103. In Figures 8 and 9, reference numeral 108 designates a radiant heat shielding plate and reference numeral 110 designates wheels to move the truck 109.

The inside structure of the first lance 101 and the second lance 102 is shown in Figures 10 to 13. The first lance 101 includes an outer conduit 128 and an inner conduit 127 which is disposed coaxially within the outer conduit 128 in a spaced relation therewith. The outer surface of the conduit 128 is covered with a heat insulating material. The second lance 102 includes an outer shell 118, an intermediate conduit 119, and an inner conduit 120 which are disposed coaxially in a spaced relation with each other.

As shown in Figure 12, the first lance 101 is provided with three guide shoes 114 radially extending from the outer conduit 128 which are to be supported by a ring 116 mounted on the front end of the second lance 102 so that the first lance 101 may slide into or out of the second lance 102. In this manner, the first lance 101 is supported by the second lance 102. The front end of the first lance 10 1 is provided with a cap 112 which is detachable and covered with a heat insulating material 113 and has an opening 13 1. The cap 4i i GB 2 124 519 A 5 112, which is connected to a hose 129 extending within the first lance 101 and the second lance 102 includes a nozzle 132 for spraying repairing materials, the nozzle orifice being directed towards the opening 13 1. At the rear end of the first lance 101, there is a hose 125 for supplying cooling liquid and a chain 121 for driving the first lance 101. The chain 121 moves along a chain guide 122 arranged in the longitudinal direction of the second lance 102 when it is driven. Therefore, the first lance 10 1 slides into the second lance 102 so as to make the entire length of the lance shorter if the chain 121 is pulled by a driving means (not shown). Conversely, the first lance 10 1 extends from the second lance 102 so as to make the entire length of the lance longer if the chain is pushed.

The cooling liquid flow lines are different in the first lance 101 and the second lance 102. As shown by the arrows in Figure 10, the liquid for cooling the first lance 101 is fed from the hose 125 and circulates through the first lance 10 1 flowing in a channel between the inner conduit 127 and the hose 129, returning via a channel between the inner conduit 127 and the outer conduit 128 through an opening 115 provided at the front end of the lance 101, and being discharged to the second lance 102 from a port 126. The cooling liquid is then discharged outside the cooling liquid supply line from the end of the second lance. The liquid for cooling the second lance 102 is fed from a conduit 124 and circulates through the second lance 102 flowing in a channel between the shell 118 and the intermediate conduit 119, returning via a channel between the intermediate conduit 119 and the inner conduit 120 through an opening 117 and being discharged outside the cooling liquid supply line passing through a port 123 and the end of the secondlance.

The apparatus as shown in Figures 8 to 13 is in a form for spraying repairing materials. It may be used in a similar manner as that described above by arranging a reflector, an image guide, a nozzle for spraying the repairing materials and the like within the lance as shown in Figure 6. In a preferable method of using the apparatus, the apparatus is first used as an inspection device by removing the hose 129 and the nozzle 132 from the lance and arranging the optical system, i.e. the reflector, the image guide etc. as shown in Figure 6 within the lance where the hose 129 and the nozzle 132 are removed. If damaged areas of a wall of the coke oven are detected, the lance is taken out of the coke oven and the optical system is exchanged for the hose 129 and the nozzle 132. Then, the lance is inserted into the coke oven and located at the positions where the damage was detected and used to spray the repairing material to the damaged areas on the wall. In this instance, the front end of the lance can be located at the exact positions where the damage was detected if a pulse motor is used as a driving means for the lance.

Referring to Figures 14 and 15, there is shown a modified form of lance supporting apparatus 103. In this embodiment, the second lance 102 is horizontally supported by six rollers 106 which are radially disposed in bearings 134 on the lance supporting apparatus 103. The second lance 102 is moved horizontally and vertically in the same manner as the preceding embodiment shown in Figures 8 and 9. Reference numeral 133 denotes a jack for regulating the angle of inclination of the second lance 102 within a range of approximately 301 either upwardly or downwardly from the horizontal position.

As explained above, by employing the teaching of the present invention, it is possible to repair damaged areas on a wall while observing the image transmitted through the image guide or taken by the television through the image guide or taken by the television camera outside the coke oven by means of the optical devices or monitor television receiver. Accordingly, the repair work can be conducted quickly and reliably without having to enter into the inside of the coke oven. Therefore, wastage of the repairing material can be minimised, and also manual work in repairing the damage to the wall can be saved as compared with erstwhile processes.

Claims

1. A method of repairing a damaged wall of a combustion chamber or coke oven which.

comprises; inserting a lance into the chamber; inspecting the condition of the wall by means of an optical system within the lance; transmitting an image of the wall condition to a location outside the chamber; and spraying repairing materials via the lance through a nozzle on to any damaged areas detected.

2. A method as claimed in Claim 1 in which the lance is moved vertically and horizontally to scan the wall. 105

3. A method as claimed in Claim 1 or Claim 2 in which the image of the wall condition is observed outside the chamber and the repairing materials are sprayed simultaneously or subsequently on to damaged areas as necessary. 110

4. A method as claimed in Claim 1 or Claim 2 in which the locations of damaged areas of the wall are recorded and the lance is subsequently repositioned at the recorded locations to spray the repairing materials on to the damaged areas.

5. A method as claimed in Claim 4 in which the precise size and shape of the damaged areas are recorded in a magnetic recording device, and the lance is moved so as to retrace automatically the damaged areas in response to instructions based on the information stored in the recording device in order to spray the repairing materials on to the damaged areas.

6. A method as claimed in any preceding claim in which the damaged area on the wall is subjected to abrasion prior to spraying the repairing materials.

7. A method as claimed in Claim 6 in which the abrasion is conducted by blasting fine particulate materials from the nozzle.

6 GB 2 124 519 A 6

8. A method as claimed in Claim 7 in which the fine particulate material comprises corundum, emery, garnet, quartz sand, spinel, alumina, zirconia, silicon carbide, boron carbide, boron 5 nitride, grit or shot.

9. A method as claimed in Claim 7 or Claim 8 in which the fine particulate material is 0.1 to 5 mm in diameter.

10. A method as claimed in any of Claims 7 to 9 in which the fine particulate material is sprayed under the pressure of 2 to 20 kg/cml G.

11. A method as claimed in any preceding claim in which the repairing material is sprayed together with water.

12. A method as claimed in any of Claims 1 to in which the repairing material is sprayed together with air.

13. A method as claimed in any of Claims 1 to 10 in which the repairing material is sprayed in the molten state together with a carrier gas.

14. A method as claimed in any preceding claim in which the detection of the damage to the wall is effected by blowing air on to the wall.

15. A method of repairing a damaged wall substantially as herein specifically described with reference to and as shown in any of the accompanying drawings.

16. Apparatus for repairing a damaged wall of a combustion chamber or coke oven which comprises a lance including an optical system, an elongate conduit and a nozzle, the optical system comprising means for transmitting an image of the wall condition to a location outside the chamber when the lance is within the chamber, and the conduit being arranged to connect the nozzle to a source of repairing material whereby the repairing material may be sprayed on to the damaged areas.

17. Apparatus as claimed in Claim 15 in which the optical system includes a condensing portion located an an opening at the end of the lance for focusing the image.

18. Apparatus as claimed in Claim 16 or Claim 17 in which the means for transmitting the image includes an optical fibre running the length of the lance.

19. Apparatus as claimed in any of Claims 16 to 18 in which the means for transmitting the image includes a television camera.

20. Apparatus as claimed in any of Claims 16 to 19 in which the means for transmitting an image comprises a light source, a first light guide directing light from the source on to the wall, a lens focusing an image of the illuminated portion of the wall on to a second light guide, and a television screen displaying the image in the second light guide.

2 1. Apparatus as claimed in any of Claims 16 to 20 in which the lance further includes cooling water circulating system.

22. Apparatus as claimed in any of Claims 16 to 21 in which the lance includes a first tube and a second tube in which the first tube is telescopically located.

23. Apparatus as claimed in any of Claims 16 to 22 in which the nozzle and the optical system are removable.

24. Apparatus for repairing a damaged wall constructed and arranged substantially as herein specifically described with reference to and as shown in any of the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1984. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

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